Conventionally, there has been provided a power supply device with a DC power supply circuit configured to output DC power, which is configured to determine whether or not a ground fault has occurred at a post-stage of the DC power supply circuit, and stop an output from the DC power supply circuit when occurrence of the ground fault is determined (e.g., see JP 3480307 B2).
Here, an output voltage from the DC power supply circuit is decreased according to the occurrence of the above-mentioned ground fault. Therefore, as a method for determining the occurrence of the ground fault, it is considered that the occurrence of the ground fault is determined when the output voltage from the DC power supply circuit falls below a prescribed reference voltage.
However, when the DC power supply circuit performs constant power operation or constant current operation, the output voltage from the DC power supply circuit is changed even while the ground fault is absent. Accordingly, erroneous determination may be easily caused, if determining presence or absence of the ground fault, using only the output voltage from the DC power supply circuit.
Conventionally, in order to prevent the erroneous determination, an output current from the DC power supply circuit is used for determination in addition to the output voltage from the DC power supply circuit. Stop of the output is further maintained only in a case where the ground fault is still detected even when operation, in which the output is restarted after temporarily stopped according to detection of the ground fault, is repeated during a prescribed period.
In the conventional example as above, there is a possibility that an overcurrent is generated when the output is restarted within the prescribed period, and accordingly fusing of a fuse occurs.